I shot a bow for 30 years before I met Dan Quillian and he introduced me to bare shaft tuning. Solved all my problems.
I noticed while checking out broadheads that Three Rivers has a kit of several spines for tuning. I was looking at wood, but maybe they have them for other materials too.
I just finished tuning my dozen broadhead arrows this morning. After confirming that I have the right spine by bare-shafting, I put broadheads on and found I needed more weight on one batch to compensate for a length adjustment, added 190 Ribteks, Tuskers, and Grizzlys and they flew perfectly.
Which reminds me, bare shaft tuning should only be done with field points, not with broadheads.